Dioscorea polystachya Turcz.

Chinese yam

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New England Distribution

Adapted from BONAP data

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North America Distribution

Adapted from BONAP data

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Facts About

Chinese yam, native to east Asia, is planted as a garden ornamental in North America. It is occasionally found in waste areas, compost piles or fields in Connecticut, Massachusetts and Vermont. The stems twine in a clockwise direction.

Habitat

Anthropogenic (man-made or disturbed habitats), meadows and fields

Characteristics

Habitat
terrestrial
New England state
  • Connecticut
  • Massachusetts
  • Vermont
Leaf arrangement
  • alternate: there is one leaf per node along the stem
  • opposite: there are two leaves per node along the stem
  • whorled: there are three or more leaves per node along the stem
Leaf blade shape
  • the leaf blade is cordate (heart-shaped with backward-facing rounded lobes), or sagittate (arrow-shaped with backward-facing pointed lobes)
  • the leaf blade is ovate (widest below the middle and broadly tapering at both ends)
  • the leaf blade is triangular, with the stalk or attachment point on one of the sides
Leaf blade length
30–90 mm
Flower petal color
  • green to brown
  • white
  • yellow
Flower petal length
13–20 mm
Petal fusion
  • the perianth parts are fused to form a tube, cup, or bell shape
  • the perianth parts are separate
Inflorescence type
  • the flowers grow out of the axil (point where a branch or leaf is attached to the main stem)
  • the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
  • the inflorescence is in the form of a compact cluster of flowers
Ovary position
the ovary is below the point of petal and/or sepal attachment
Fruit type (specific)
the fruit is a capsule (splits along two or more seams, apical teeth or pores when dry, to release two or more seeds)
Fruit length
12–20 mm
Show All Characteristics
  • Clonal plantlets
    Axillary bulblets
    there are bulblets in some axils
  • Flowers
    Anther attachment
    the anther is attached by its base to the filament
    Bulblets replace flowers
    there are no bulblets where the flowers are located
    Carpels fused
    the carpels are fused (the number of carpels equals the number of locules)
    Flower bracts
    there are bracts associated with the flower
    Flower number
    1–8
    Flower orientation
    the flowers point upward or spread or curve outward
    Flower petal color
    • green to brown
    • white
    • yellow
    Flower petal length
    13–20 mm
    Flower shape
    • the flower is bell-shaped
    • the flower is cup-shaped
    Flower symmetry
    there are two or more ways to evenly divide the flower (the flower is radially symmetrical)
    Form of style
    the style is branched above the base
    Fringed petal edges
    the petals are not fringed
    Hairs on flower stalk
    the flower stalk has no hairs on it
    Inflorescence hair glands
    the axis of the inflorescence has no hairs on it
    Inflorescence length
    20–100 mm
    Inflorescence type
    • the flowers grow out of the axil (point where a branch or leaf is attached to the main stem)
    • the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
    • the inflorescence is in the form of a compact cluster of flowers
    Length of flower stalk
    At least 0 mm
    Length of peduncle
    0 mm
    Marks on petals
    the petals have spots or streaks on them
    Nectar spur
    the flower has no nectar spurs
    Number of carpels
    3
    Number of pistils
    3
    Number of sepals and/or petals
    there are six petals, sepals or tepals in the flower
    Number of styles
    3
    Ovary position
    the ovary is below the point of petal and/or sepal attachment
    Petal and sepal arrangement
    the flower includes only one cycle of petals or sepals
    Petal appearance
    the petals are thin and delicate, and pigmented (colored other than green or brown)
    Petal base
    the petal narrows gradually or does not narrow at the base
    Petal fusion
    • the perianth parts are fused to form a tube, cup, or bell shape
    • the perianth parts are separate
    Petal hairs on inner/upper surface
    there are no hairs on the inner/upper petal surface
    Petal nectaries
    there are nectaries at the petal bases
    Sepal appearance
    the sepals resemble petals in color and texture
    Sepal length
    1.3–2 mm
    Sepal orientation
    • the sepals are pressed against the plant, or jutting stiffly upward
    • the sepals are slightly curved outwards from the plant
    Sepals fused only to sepals
    • the sepals are fused to each other (often along with the petals in monocots), at least near their bases
    • the sepals are separate from one another
    Spathe
    the plant does not have a spathe
    Spathe form
    NA
    Spathe length
    0 mm
    Stamen number
    6
    Stamen position relative to petals
    NA
    Stamen types
    the stamens within a cycle are distinctly of two types
    Stamens fused
    the stamens are fused to one another at or near their bases
    Stamens fused outwards
    the stamens are fused to the petals or tepals at or near their bases
    Style petal-like
    the style is not broad and flattened like a petal
    Tepals
    the petals and sepals are similar in size and color
  • Fruits or seeds
    Berry color
    NA
    Capsule ridges
    there are three ribs or wings on the capsule
    Fruit compartments
    there are three locules in the fruit
    Fruit length
    12–20 mm
    Fruit type (general)
    the fruit is dry and splits open when ripe
    Fruit type (specific)
    the fruit is a capsule (splits along two or more seams, apical teeth or pores when dry, to release two or more seeds)
    Fruit width
    12–20 mm
    Other markings on berry
    NA
  • Glands or sap
    Sap
    the sap is clear and watery
  • Growth form
    Lifespan
    the plant lives more than two years
    Root septa
    the roots do not have transverse septa
    Underground organs
    the plant has one or more swollen storage organs underground, such as bulbs, tubers or corms
  • Leaves
    Hairs on underside of leaf blade
    the underside of the leaf is not hairy, or has very few hairs
    Hairs on upper side of leaf blade
    the upper side of the leaf is not hairy, or has very few hairs
    Leaf arrangement
    • alternate: there is one leaf per node along the stem
    • opposite: there are two leaves per node along the stem
    • whorled: there are three or more leaves per node along the stem
    Leaf blade basal lobes
    the leaf blades are lobed at their bases
    Leaf blade base
    the leaf has a distinct leaf stalk (petiole)
    Leaf blade base shape
    • The base of the leaf blade is cordate (heart-shaped, with rounded lobes) or sagittate (arrow-shaped, with pointed, backward-facing lobes)
    • the base of the leaf blade is truncate (ends abruptly in a more or less straight line as though cut off)
    Leaf blade bloom
    the underside of the leaf blade has no noticeable waxy or powdery bloom
    Leaf blade cross-section
    the leaf blade is more or less flat in cross-section
    Leaf blade faces
    both surfaces of the leaf blade are exposed
    Leaf blade form
    Fully-formed (i.e., expanded), +/- green leaf blades are found somewhere on the plant
    Leaf blade length
    30–90 mm
    Leaf blade orientation
    the upper surface of the leaf blade faces the stem of the plant
    Leaf blade shape
    • the leaf blade is cordate (heart-shaped with backward-facing rounded lobes), or sagittate (arrow-shaped with backward-facing pointed lobes)
    • the leaf blade is ovate (widest below the middle and broadly tapering at both ends)
    • the leaf blade is triangular, with the stalk or attachment point on one of the sides
    Leaf blade surface colors
    the upper side of the leaf blade is relatively uniform in color
    Leaf blade tip
    • the tip of the leaf blade is acuminate (tapers to a long, thin point)
    • the tip of the leaf blade is caudate (has a very long tail-like projection ending in a point)
    Leaf blade veins
    the lateral veins are parallel or slightly arched in the direction of the tip
    Leaf blade width
    30–110 mm
    Leaf stalk length
    20–30 mm
    Leaf type
    the leaves are simple (i.e., lobed or unlobed but not separated into leaflets
    Leaflet number
    0
    Stipule twining
    NA
    Stipules
    there are no stipules on this plant
  • Place
    Habitat
    terrestrial
    New England state
    • Connecticut
    • Massachusetts
    • Vermont
    Specific habitat
    • man-made or disturbed habitats
    • meadows or fields
  • Scent
    Plant odor
    the leaves have no particular smell
  • Stem, shoot, branch
    Flowering stem growth form
    the flowering stem trails along the ground or on other vegetation, or floats in the water
    Flowering stem leaves
    there is at least one fully-formed leaf on the flowering stem
    Stem hairs
    the stem is nearly or completely hairless

Wetland Status

Not classified

New England Distribution and Conservation Status

Distribution

Connecticut
present
Maine
absent
Massachusetts
present
New Hampshire
absent
Rhode Island
absent
Vermont
present

Conservation Status

None

Native to North America?

No

Sometimes Confused With

Dioscorea villosa:
leaves with unlobed blades, lacking bulbils in the axils, and alternate in the distal portion of the stem, and plants with rhizomes (vs. D. polystachya, with leaves with 3- to 5-lobed blades, with bulbils in the axils, and usually opposite in the distal portion of the stem, and plants tuberous).

Family

Dioscoreaceae

Genus

Dioscorea

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Information from Dichotomous Key of Flora Novae Angliae

1.  Dioscorea polystachya Turcz. E

Chinese yam. Dioscorea batatas R. Decr. • CT, MA, VT. Waste places, compost heaps, fields. The name Dioscorea oppositifolia L. has been used for this species, but that name correctly refers to a plant that is native to India and not found in New England (Raz 2002).